It depends on the Pokemon you are hatching.
you can't hatch a pikachu egg on diamond, it hatches in to a pichu.
It takes 9,180 steps or 36 Egg Cycles to hatch an Eevee.
All you have to do is walk around until it hatches. Each Pokemon has a different number of steps required for it to hatch.
in order to hatch a riolu egg you need to walk about 5,000-6,000 steps
5,120 steps. I like Pokemon so much that i almost played every Pokemon game
It depends on the Pokemon you are hatching.
you can't hatch a pikachu egg on diamond, it hatches in to a pichu.
about 7,000 steps
It takes 9,180 steps or 36 Egg Cycles to hatch an Eevee.
All you have to do is walk around until it hatches. Each Pokemon has a different number of steps required for it to hatch.
You have to have the egg with you and walk several thousand steps.
About 10,000 steps. If you don't believe, then check your Pokemon handbook (instructions booklet).
it takes some more than 10000 steps to hatch an happiny egg
The number of steps needed to make a egg hatch in Pokemon Diamond depends on what the Pokemon is. On average it can take roughly 6000 steps to hatch an egg. You can cut the number of steps need in half by having a Pokemon with the ability Flame Body or Magma Armor in your team with the egg.
in order to hatch a riolu egg you need to walk about 5,000-6,000 steps
5120, courtesy of serebii.net pokedex (check base egg steps)